The disease which is transmitted from animals to humans are called zoonotic disease. So in zoonosis, the primary reservoirs are animals for example in rat-bite fever is the zoonotic disease which is spread by rats.
Bacteria, fungi, virus, protozoa can be the causative agent of the zoonotic disease. When the disease gets into humans then this disease can be spread from humans to humans if the disease is contagious. So here as rat is the primary reservoir therefore the correct answer is a zoonosis.
and it's name is Hydronium. Hope this helps :)
